San Leandro police Sgt. Ted Henderson said 29-year-old Detwone Watson is being held on a warrant charging him with attempted murder, two counts of attempted robbery, and one count of robbery in connection with the shooting, which occurred at about 1:50 a.m. on Nov. 25 in the parking lot of the store at 15555 Hesperian Blvd.

Another suspect, 20-year-old Oakland resident Tony Phillips, is already in custody, and police are seeking two others in the case.

Watson will likely be arraigned on Monday, Henderson said.

Henderson said police headed to the home in East Oakland, near 106th Avenue and MacArthur Boulevard, early Thursday morning after a confidential informant told them that Watson was there.

The informant had been partying with Watson and called police after Watson passed out around 2 a.m., Henderson said.

Investigators believe that on the morning of the shooting, Watson and Phillips were passengers in a two-door burgundy Buick Riviera that pulled up in the full parking lot behind the three victims, all cousins from San Leandro in their early 20s, Henderson said last month.

The victims—Christopher, Rafael and Javier Murillo—had been standing by their car in the parking lot. They had gone to Walmart looking for a video game, but left the store when they could not find it, police said.

Police believe Watson brandished a gun as he approached Christopher Murillo, and that Phillips approached Rafael Murillo, who was wearing a gold necklace, and attempted to steal it.

According to police, a fight ensued between Phillips and Rafael Murillo, and Javier Murillo allegedly tried to help his cousin by holding down Phillips. A third suspect exited the Buick and attempted to help Phillips.

Police said Watson then allegedly shot Christopher Murillo, striking him in the neck.

The third suspect fled on foot and the shooter got back in the Buick and drove off with the driver, leaving Phillips with the victims, who detained him until police arrived, Henderson said.

KCBS’ Bob Melrose Reports:

Henderson said police were told that Watson wasn’t armed today, but will check the house in East Oakland to make sure that there isn’t a gun there.

He said Watson lives elsewhere in Oakland but that police believe that the gun he allegedly used in the Black Friday incident might be there.

(Copyright 2011 by CBS San Francisco. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)